1. Technical Field
The invention relates to a system, apparatus and methods for high-speed testing of analog-to-digital converters.
2. Discussion of the Related Art
Production testing of analog-to-digital converters (ADCs) using analog testing techniques can be very time consuming. For example, complete testing of all circuit elements in a 10-bit ADC would require 210 (i.e., 1024) tests at discrete analog voltage levels to completely test the hardware circuitry of the ADC. The complete testing of an ADC using such methods can take several hours, and testing of higher resolution ADCs would take correspondingly longer times.
Because of the prohibitively long times associated with complete testing of ADCs, only partial testing of an ADC is typically carried out during manufacture. In partial testing, only a limited set of pre-selected conversion codes are tested, and it is assumed that if the device works for the limited set of codes it will likely work for all conversion codes. However, partial testing can only ensure that hardware relating to the selected codes performs as expected, and there is no guarantee that untested hardware relating to non-selected codes will work. Since only a few codes of the total possible 1024 codes are used in testing, there is a high probability that an ADC that is considered to have passed production testing may fail during normal use.